The present invention relates to an improved sight window, designed for use in a large variety of situations. Such windows are commonly used in sidewalls of vessels to enable a workman to observe from one side of the wall, activities or conditions existing on the opposite side.
Sight windows are conventionally installed in machines and vessels by installing the window in a separate housing and, thereafter, securing the housing and its window, across the opening in the vessel sidewall, to the sidewall with studs or bolts. This is a much more expensive and less sanitary way of installing sight windows to the walls in which the sight window is needed, as compared to my invention.
The closest prior art of which I am aware is the manufacture and use, of such housings, which are bolted to such walls. The four patents issued to Charles E. Meginnis under U.S. Pat. Nos. 3,345,872; 3,625,390; 4,169,309; and 4,206,537, are representative of this known current prior art. Most, if not all, of these patents disclose and claim the mounting of a sight window, with or without one or more liners, within a separate housing, and thereafter securing such housings with the windows previously installed therein, to the surface of the vessel wall and across the sight window-opening in the wall. In each such instance, the windowpane (or lens, as used in said patents) is not in contact with the opening-defining portions of the sidewall, but instead, is mounted in spaced relation thereto upon the exterior surface of the sidewall.